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In this paper, we propose a backstepping based nonlinear guidance controller, designed for 3-D path tracking for a UAV. The guidance law design assumes first order dynamics for the speed, heading and elevation angles. We demonstrate closed loop stability via Lyapunov analysis. The efficacy of the controller is demonstrated for two cases, namely the straight path following and a curved path following.
A collision avoiding system and a method of safety flying is proposed in this paper for Unmanned Air Vehicles (UAV). The UAV accesses the data from various sensors mounted on board and thus calculates the risks factors for any impending collision. An algorithm for decision making in order to avoid collision is presented in this paper as a pseudo code. Based on the measured as well as estimated risk...
Based on the developed nonlinear dynamic equations of a quadrotor (named as Qball-X4) UAV (Unmanned Aerial Vehicle), attitude and trajectory tracking control designs based on an inner/outer loop control structure has been proposed in this paper. Feedback linearization is designed to control the attitude stability in inner loop, traditional PID is designed to follow trajectory in accordance with pre-planned...
In this paper, a method to calculate alerting thresholds is outlined along with the assumptions and an example. First, the definitions and recommendations of the FAA sponsored Sense-and-Avoid (SAA) workshop report has been adapted to a formal mathematical definition. These definitions are then realized using assumptions and other logic and are translated into a more concrete SAA scenarios. Alerting...
This paper presents a methodology based on a variation of the Rapidly-exploring Random Trees (RRTs) that generates feasible trajectories for autonomous vehicles with holonomic constraints in environments with obstacles. Our approach is based on seventh order Bézier curves to connect vertexes of the tree, generating paths that do not violate the main kinematic constraints of the vehicle. The methodology...
This paper presents a trajectory tracking control design which provides the essential spatial-temporal feedback control capability for fixed-wing unmanned aerial vehicles (UAVs) to execute a time critical mission reliably. In this design, a kinematic trajectory tracking control law and a control gain selection method are developed to allow the control law to be implemented on a fixed-wing UAV based...
The utilization of unmanned aerial vehicles requires the ability to navigate in urban or unknown terrain where many moving and/or stationary obstacles of different types and sizes may endanger the safety of the mission. Large efforts have been addressed to resolve conflicts to unmanned aircraft. This paper explores the fundamental concept and presents an up-to-date survey of the collision sensing,...
This paper presents a quadrocopter flying in rhythm to music. The quadrocopter performs a periodic side-to-side motion in time to a musical beat. Underlying controllers are designed that stabilize the vehicle and produce a swinging motion. Synchronization is then achieved by using concepts from phase-locked loops. A phase comparator combined with a correction algorithm eliminate the phase error between...
Many robotic control tasks involve complex dynamics that are hard to model. Hand-specifying trajectories that satisfy a system's dynamics can be very time-consuming and often exceedingly difficult. We present an algorithm for automatically generating large classes of trajectories for difficult control tasks by learning parameterized versions of desired maneuvers from multiple expert demonstrations...
This paper addresses the problem of robust takeoff and landing control of a quadrotor UAV (Unmanned Aerial Vehicle). During the critical flight phases of takeoff and landing the vehicle dynamics change according to the possible existence of contact with the ground. To model the vehicle during the overall maneuver a hybrid automaton is used where each state corresponds to a different dynamic behavior...
In this paper a Constrained Finite Time Optimal Controller (CFTOC) for the problem of trajectory tracking of an Unmanned quadrotor Helicopter (UqH) is presented. The controller is designed based on a Piecewise modeling of the quadrotor for the rotational angles, that are inherently coupled to the translation equations of motion. The proposed CFTO-control scheme is able to take under certain factors...
A trajectory tracking control system for a fixed-wing unmanned aerial vehicle (UAV) is designed in this paper. A nonlinear model with total variables of UAV is introduced, and the corresponding longitudinal linear model and lateral linear model are obtained by using small perturbation method. The trajectory control system is composed of guidance part and attitude control part. The guidance law is...
To the problem of cooperative ground moving target tracking using UAVs in an urban area, a novel method is presented, which based on target state fusion estimation and prediction, as well as on-line trajectory planning. Firstly, based on active sensing, a solving framework was presented, the formal representation and system model of cooperative target tracking using a team UAVs was established; secondly,...
This paper presents an innovative 3D analytical algorithm for the resolution of the pair-wise non-cooperative collision avoidance problem between aircrafts. The proposed algorithm addresses the above described problem by using an innovative approach, based on the consideration of a cylindrical safety bubble, and it is able to obtain an optimal three-dimensional analytical solution for this problem...
We perform a simulation study to compare the performance of several of single-camera mapping and localisation algorithms for a search and rescue application using low-speed, low-altitude UAVs. We investigate the effects of a range of conditions including target location, nadir angle of the camera and the trajectory of the UAV on three bearings-only SLAM algorithms: Delayed Initialisation (DI), Inverse...
Synthetic Aperture Radar (SAR) equipment is an all-weather radar imaging system that can create high resolution images by means of utilising the movement of the flying platform. Accurate knowledge of the flown trajectory is essential in order to get focused images. Recently SAR systems are becoming more used on smaller and cheaper flying platforms like Unmanned Aerial Vehicles (UAV). Since UAVs in...
Aerial recovery of micro air vehicles (MAVs) presents a challenging problem in multi-vehicle dynamics and control. This paper presents a method for recovering MAVs in flight using a mothership and towed drogue, in which the mothership executes an orbit that places the drogue in a stable, slower orbit that can be tracked by a MAV. The differential flatness property of the system is exploited to calculate...
In this paper, we consider a differential game theoretic approach to compute optimal strategies by a team of UAVs to evade the attack of an aerial jammer on the communication channel. We formulate the problem as a zero-sum pursuit-evasion game. The cost function is the termination time of the game. We use Isaacs' approach to derive the necessary conditions to arrive at the equations governing the...
Receding Horizon (RH) control is an established control methodology which has been used successfully for many control applications. More recently it has been applied for autonomous vehicle guidance. Its successful implementation, in particular for applications involving agile vehicles like rotorcraft, hinges on two critical factors: (1) adequately accounting for the vehicle dynamics to guarantee that...
Based on extended set-membership filter (ESMF) and the path planning method in relative velocity coordinates (RVCs), a new 3D multiple Unmanned Aerial Vehicle (UAV) systems active cooperative observation method, high precision cooperative observing a moving target by proper planning the behavior of each member vehicle, is proposed. The new method combines the ESMF based cooperative observation method...
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